def make_tree(graph, source, edge_weight = None):
parent = ydict(backend=graph)
heap = yheap(backend=graph)
distance = ydict(backend=graph)
u, distance[u] = source, 0
while True:
for e in graph.edges(source = u):
if edge_weight[e] < 0:
raise NegativeEdgeWeightError(e)
v = other_vertex(e,u)
distance_to_v = distance.get(v)
relaxed_length = distance[u] + edge_weight[e]
if distance_to_v is None or relaxed_length < distance_to_v:
parent[v] = e
distance[v] = relaxed_length
if v in heap:
heap.modifykey(v, relaxed_length)
else:
heap.insert(v, relaxed_length)
try:
u = heap.deletemin()
except:
return parent
def __init__(self, graph, edge_weight):
self.__graph = graph
self.__edge_weight = edge_weight
self.__priority_queue = yheap(backend=graph)
self.__vertex_state = ydict(backend=graph)
def __init__(self, graph, vertex_heuristic):
self.__graph = graph
self.__h = vertex_heuristic
self.__priority_queue = yheap(backend=graph)
self.__vertex_state = ydict(backend=graph)